Imaging lens having five lens elements and electronic apparatus having the same

ABSTRACT

An optical imaging lens includes, from an object side to an image side, an aperture stop, first, second, third, fourth, and fifth lens elements. The first lens element has a positive refracting power, its object-side surface has a convex portion in a vicinity of an optical axis, and its image-side surface has a concave portion in the vicinity of the optical axis. The second lens element has a negative refracting power, and its image-side surface is concave. The fourth lens element has a convex image-side surface. The object-side surface of the fifth lens element has a convex portion in the vicinity of the optical axis, and the image-side surface of the fifth lens element has a concave portion in the vicinity of the optical axis.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/617,304, filed Sep. 14, 2012, which claims priority to TaiwaneseApplication No. 101111478, filed Mar. 30, 2012, the disclosures of whichare incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an imaging lens and an electronicapparatus, more particularly to an imaging lens having five lenselements and an electronic apparatus having the same.

2. Description of the Related Art

In recent years, as use of portable electronic devices (e.g., mobilephones and digital cameras) becomes ubiquitous, much effort has been putinto reducing dimensions of portable electronic devices. Moreover, asdimensions of charged coupled device (CCD) and complementary metal-oxidesemiconductor (CMOS) based optical sensors are reduced, dimensions ofimaging lenses for use with the optical sensors must be correspondinglyreduced without significantly compromising optical performance.

In view of the above, each of Taiwanese Patent Publication Nos.201022714, 201137430, and 201043999 discloses a conventional imaginglens with five lens elements, of which the first, second, and third lenselements have positive, negative, and positive refracting powers,respectively. Further, U.S. Patent Application Publication No.20110249346 discloses a conventional imaging lens with five lenselements, each of which has a relatively large thickness and is spacedapart from an adjacent one of the lens elements by a relatively widegap.

U.S. Patent Application Publication No. 20110013069 and Taiwanese PatentPublication Nos. 201144890 and 201106040 also disclose conventionalimaging lenses with five lens elements.

Although the above conventional imaging lenses have reduced overalllengths, some of them may still be too long. For example, theconventional imaging lens disclosed in Taiwanese Patent Publication No.201144890 has an overall length of 6.5 mm, which may be too long forcertain miniaturized portable electronic devices.

Thus, it is apparent that the current trend in development of imagingsystems for portable electronic devices focuses on reducing overalllengths of the imaging systems. However, optical performances andimaging qualities of the imaging systems may be compromised as theoverall lengths are reduced.

BRIEF SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide an imaginglens having a shorter overall length while maintaining good opticalperformance.

Accordingly, an imaging lens of the present invention includes first,second, third, fourth, and fifth lens elements arranged from an objectside to an image side in the given order. Each of the first, second,third, fourth, and fifth lens elements has an object-side surface facingtoward the object side and an image-side surface facing toward the imageside.

The first lens element has a positive refracting power, and theobject-side surface thereof is a convex surface. The second lens elementhas a negative refracting power, and the image-side surface thereof is aconcave surface. The third lens element has a negative refracting power.The image-side surface of the fourth lens element is a convex surface.The image-side surface of the fifth lens element has a concave portionin a vicinity of an optical axis of the imaging lens and a convexportion in a vicinity of a periphery of the fifth lens element.

The imaging lens satisfies |v₂−v₃|<10 and 0.5<T₄/G_(AA)<1.0, where:

“v₂” represents an Abbe number of the second lens element;

“v₃” represents an Abbe number of the third lens element;

“T₄” represents a distance between the object-side surface and theimage-side surface of the fourth lens element at the optical axis; and

“G_(AA)” represents a sum of a distance between the image-side surfaceof the first lens element and the object-side surface of the second lenselement at the optical axis, a distance between the image-side surfaceof the second lens element and the object-side surface of the third lenselement at the optical axis, a distance between the image-side surfaceof the third lens element and the object-side surface of the fourth lenselement at the optical axis, and a distance between the image-sidesurface of the fourth lens element and the object-side surface of thefifth lens element at the optical axis.

Another object of the present invention is to provide an electronicapparatus having an imaging lens with five lens elements.

Accordingly, an electronic apparatus of the present invention includes:

a housing; and

an imaging module disposed in the housing, and including the imaginglens of the present invention, a barrel on which the imaging lens isdisposed, a seat unit on which the barrel is disposed, and an imagesensor disposed at the image side and operatively associated with theimaging lens for capturing images.

BRIEF DESCRIPTION OF THE DRAWINGS

Other features and advantages of the present invention will becomeapparent in the following detailed description of the preferredembodiments with reference to the accompanying drawings, of which:

FIG. 1 is a schematic diagram that illustrates the first preferredembodiment of an imaging lens according to the present invention;

FIG. 2 shows values of some optical parameters corresponding to theimaging lens of the first preferred embodiment;

FIG. 3 shows values of some parameters of an optical relationshipcorresponding to the imaging lens of the first preferred embodiment;

FIGS. 4( a) to 4(d) show different optical characteristics of theimaging lens of the first preferred embodiment;

FIG. 5 is a schematic diagram that illustrates the second preferredembodiment of an imaging lens according to the present invention;

FIG. 6 shows values of some optical parameters corresponding to theimaging lens of the second preferred embodiment;

FIG. 7 shows values of some parameters of the optical relationshipcorresponding to the imaging lens of the second preferred embodiment;

FIGS. 8( a) to 8(d) show different optical characteristics of theimaging lens of the second preferred embodiment;

FIG. 9 is a schematic diagram that illustrates the third preferredembodiment of an imaging lens according to the present invention;

FIG. 10 shows values of some optical parameters corresponding to theimaging lens of the third preferred embodiment;

FIG. 11 shows values of some parameters of the optical relationshipcorresponding to the imaging lens of the third preferred embodiment;

FIGS. 12( a) to 12(d) show different optical characteristics of theimaging lens of the third preferred embodiment;

FIG. 13 is a schematic diagram that illustrates the fourth preferredembodiment of an imaging lens according to the present invention;

FIG. 14 shows values of some optical parameters corresponding to theimaging lens of the fourth preferred embodiment;

FIG. 15 shows values of some parameters of the optical relationshipcorresponding to the imaging lens of the fourth preferred embodiment;

FIGS. 16( a) to 16(d) show different optical characteristics of theimaging lens of the fourth preferred embodiment;

FIG. 17 is a table that shows values of parameters of other opticalrelationships corresponding to the imaging lenses of the first, second,third, and fourth preferred embodiments;

FIG. 18 is a schematic partly sectional view to illustrate a firstexemplary application of the imaging lens of the present invention; and

FIG. 19 is a schematic partly sectional view to illustrate a secondexemplary application of the imaging lens of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Before the present invention is described in greater detail, it shouldbe noted that like elements are denoted by the same reference numeralsthroughout the disclosure.

Referring to FIG. 1, an imaging lens 2 of the present invention includesan aperture stop 8, first, second, third, fourth, and fifth lenselements 3-7, and an optical filter 9 arranged in the given order alongan optical axis (I) from an object side to an image side. The opticalfilter 9 is an infrared cut filter for filtering infrared light tothereby reduce aberration of images formed at an image plane 10.

Each of the first, second, third, fourth, and fifth lens elements 3-7and the optical filter 9 has an object-side surface 31, 41, 51, 61, 71,91 facing toward the object side, and an image-side surface 32, 42, 52,62, 72, 92 facing toward the image side. Light entering the imaging lens2 travels through the aperture stop 8, the object-side and image-sidesurfaces 31, 32 of the first lens element 3, the object-side andimage-side surfaces 41, 42 of the second lens element 4, the object-sideand image-side surfaces 51, 52 of the third lens element 5, theobject-side and image-side surfaces 61, 62 of the fourth lens element 6,the object-side and image-side surfaces 71, 72 of the fifth lens element7, and the object-side and image-side surfaces 91, 92 of the opticalfilter 9, in the given order, to form an image on the image plane 10.Each of the object-side surfaces 31, 41, 51, 61, 71, 91 and theimage-side surfaces 32, 42, 52, 62, 72, 92 has a center point coincidingwith the optical axis (I).

The lens elements 3-7 are made of plastic material in this embodiment,and at least one of them may be made of other materials in otherembodiments.

Relationships among some optical parameters of the imaging lens 2 of thepresent invention are as follows:|v ₂ −v ₃|<10;  (1)0.5<T ₄ /G _(AA)<1.0;  (2)0.33<T ₃ /G _(AA)<0.60;  (3)5<|f ₄ /T ₄₋₅|<8;  (4)0.42<|R ₇ /f ₄|<0.62; and  (5)T ₄ >T _(L3A2-L4A1),  (6)where:“v₂” and “v₃” represent Abbe numbers of the second and third lenselements 4, 5, respectively;“T₄” represents a distance between the center points of the object-sideand image-side surfaces 61, 62 of the fourth lens element 6 (i.e., “T₄”represents a thickness of the fourth lens element 6 the optical axis(I));“G_(AA)” represents a sum of a distance between the center points of theimage-side and object-side surfaces 32, 41, a distance between thecenter points of the image-side and object-side surfaces 42, 51, adistance between the center points of the image-side and object-sidesurfaces 52, 61, and a distance between the center points of theimage-side and object-side surfaces 62, 71 (i.e.,“G_(AA)” represents a sum of widths of air gaps among the lenses 3-7 atthe optical axis (I));“T₃” represents a distance between the center points of the object-sideand image-side surfaces 51, 52 of the third lens element 5 (i.e., “T₃”represents a thickness of the third lens element 5 at the optical axis(I));“f₄” represents a focal length of the fourth lens element 6;“T₄₋₅” represents a distance between the center points of theobject-side surfaces 61, 71 of the fourth and fifth lens elements 6, 7;“R₇” represents a radius of curvature of the object-side surface 61 atthe center point thereof; and“T_(L3A2-L4A1)” represents a distance between the center points of theimage-side and object-side surfaces 52, 61 (i.e., “T_(L3A2-L4A1)”represents the width of the air gap between the third and fourth lenselements 5, 6 at the optical axis (I)).

In the first preferred embodiment, which is depicted in FIG. 1, thefirst lens element 3 has a positive refracting power, and theobject-side surface 31 and the image-side surface 32 thereof areaspherical convex surfaces.

The second lens element 4 has a negative refracting power, theobject-side surface 41 thereof has a convex portion 411 in a vicinity ofthe optical axis (I) and another convex portion 412 in a vicinity of aperiphery of the second lens element 4, and the image-side surface 42thereof is a concave surface.

The third lens element 5 has a negative refracting power, theobject-side surface 51 thereof has a convex portion 511 in a vicinity ofthe optical axis (I) and a concave portion 512 in a vicinity of aperiphery of the third lens element 5, and the image-side surface 52thereof has a concave portion 521 in a vicinity of the optical axis (I)and a convex portion 522 in a vicinity of the periphery of the thirdlens element 5.

The fourth lens element 6 has a positive refracting power, theobject-side surface 61 thereof is a concave surface, and the image-sidesurface 62 thereof is a convex surface.

The fifth lens element 7 has a negative refracting power, theobject-side surface 71 thereof has a convex portion 711 in a vicinity ofthe optical axis (I) and another convex portion 712 in a vicinity of aperiphery of the fifth lens element 7, and the image-side surface 72thereof has a concave portion 721 in a vicinity of the optical axis (I)and a convex portion 722 in a vicinity of the periphery of the fifthlens element 7.

In this embodiment, each of the object-side surfaces 31-71 and theimage-side surfaces 32-72 is aspherical. However, configurations of theobject-side and image-side surfaces 31-71, 32-72 are not limited tosuch.

The optical filter 9 is disposed between the fifth lens element 7 andthe image plane 10, and is a piece of flat glass in this embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the first preferred embodiment are as follows:|v ₂ −v ₃|=2.75;T ₄ /G _(AA)=0.71;T ₃ /G _(AA)=0.40;|f ₄ /T ₄₋₅|=6.86;|R ₇ /f ₄|=0.45.

In this embodiment, “T_(L3A2-L4A1)” is equal to 0.17, and “T₄” is equalto 0.56, which is greater than “T_(L3A2-L4A1)”. The imaging lens 2 hasan overall system focal length of 3.26 mm, a half field-of-view (HFOV)of 35.15°, and a system length of 3.68 mm. Shown in FIG. 2 is a tablethat shows values of some optical parameters corresponding to thesurfaces 31-71, 32-72 of the first preferred embodiment.

Each of the object-side surfaces 31-71 and the image-side surfaces 32-72satisfies the optical relationship of

$\begin{matrix}{{Z(Y)} = {\frac{Y^{2}}{R}/\left( {1 + \sqrt{1\left( {1 + K} \right)\frac{Y^{2}}{R^{2}}} + {\sum\limits_{i = 1}^{n}{a_{2i}*Y^{2\; i}}}} \right.}} & (7)\end{matrix}$where:“R” represents a radius of curvature of the surface;“Y” represents a perpendicular distance between an arbitrary point onthe surface and the optical axis (I);“Z” represents a distance between projections of the arbitrary point andthe center point of the surface onto the optical axis (I);“K” represents a conic constant of the surface; and“a_(2i)” represents a 2i^(th)-order coefficient of the surface.

Shown in FIG. 3 is a table that shows values of some optical parametersof the aforementioned optical relationship (7) corresponding to thefirst preferred embodiment.

FIGS. 4( a) to 4(d) show simulation results corresponding tolongitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thefirst preferred embodiment, respectively. In each of the simulationresults, curves corresponding respectively to wavelengths of 470 nm, 555nm, and 650 nm are shown.

It can be understood from FIGS. 4( a), 4(b), 4(c) and 4(d) that thefirst preferred embodiment is able to achieve a good opticalperformance.

In view of the above, with the system length reduced down to below 4 mm,the imaging lens 2 of the first preferred embodiment is still able toachieve a relatively good optical performance.

Referring to FIG. 5, the difference between the first and secondpreferred embodiments resides in that, in the second preferredembodiment, the image-side surface 32 of the first lens element 3 is aconcave surface, and the second and third lens elements 4, 5 have Abbenumbers different from those of the second and third lens elements 4, 5of the first preferred embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the second preferred embodiment are as follows:|v ₂ −v ₃|=0.64;T ₄ /G _(AA)=0.93;T ₃ /G _(AA)=0.37;|f ₄ /T ₄₋₅|=5.92;|R ₇ /f ₄|=0.47.

Further, in this embodiment, “T_(L3A2-L4A1)” is equal to 0.21, and “T₄”is equal to 0.63, which is greater than “T_(L3A2-L4A1)”.

In this embodiment, the imaging lens 2 has an overall system focallength of 3.25 mm, a half field-of-view (HFOV) of 35.36°, and a systemlength of 3.65 mm. Shown in FIG. 6 is a table that shows values of theoptical parameters corresponding to the surfaces 31-71, 32-72 of thesecond preferred embodiment. Shown in FIG. 7 is a table that showsvalues of some parameters of the aforementioned optical relationship (7)corresponding to each of the object-side surfaces 31-71 and theimage-side surfaces 32-72 of the second preferred embodiment.

FIGS. 8( a) to 8(d) show simulation results corresponding tolongitudinal spherical aberration, sagittal astigmatism aberration,tangential astigmatism aberration, and distortion aberration of thesecond preferred embodiment, respectively.

It is apparent from FIG. 8( a) that the second preferred embodiment hasa relatively low spherical aberration and a relatively low chromaticaberration at each of the wavelengths. It can be understood from FIGS.8( b), 8(c) and 8(d) that the second preferred embodiment is able toachieve a good optical performance.

In view of the above, with the system length reduced down to below 4 mm,the imaging lens 2 of the second preferred embodiment is still able toachieve a relatively good optical performance.

Referring to FIG. 9, the difference between the first and thirdpreferred embodiments resides in that, in the third preferredembodiment, the image-side surface 32 of the first lens element 3 is aconcave surface, and the second lens element 4 has an Abbe numberdifferent from that of the second lens element 4 of the first preferredembodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the third preferred embodiment are as follows:|v ₂ −v ₃|=6.02;T ₄ /G _(AA)=0.82;T ₃ /G _(AA)=0.51;|f ₄ /T ₄₋₅|=7.61;|R ₇ /f ₄|=0.47.

Further, in this embodiment, “T_(L3A2-L4A1)” is equal to 0.16, and “T₄”is equal to 0.56, which is greater than “T_(L3A2-L4A1)”.

In this embodiment, the imaging lens 2 has an overall system focallength of 3.25 mm, a half field-of-view (HFOV) of 35.26°, and a systemlength of 3.75 mm. Shown in FIG. 10 is a table that shows values of theoptical parameters corresponding to the surfaces 31-71, 32-72 of thethird preferred embodiment. Shown in FIG. 11 is a table that showsvalues of some parameters of the aforementioned optical relationship (7)corresponding to each of the object-side surfaces 31-71 and theimage-side surfaces 32-72 of the third preferred embodiment.

Referring to FIGS. 12( a) to 12(d), with the system length reduced downto below 4 mm, the imaging lens 2 of the third preferred embodiment isstill able to achieve a relatively good optical performance and areduced chromatic aberration.

Referring to FIG. 13, the difference between the first and fourthpreferred embodiments resides in that, in the fourth preferredembodiment, the image-side surface 32 of the first lens element 3 is aconcave surface, the object-side surface 51 of the third lens element 5has a concave portion 511′ in the vicinity of the optical axis (I), theimage-side surface 52 of the third lens element 5 has a convex portion521′ in the vicinity of the optical axis (I), and the second lenselement 4 has an Abbe number different from that of the second lenselement 4 of the first preferred embodiment.

Relationships among some of the aforementioned optical parameterscorresponding to the fourth preferred embodiment are as follows:v ₂ −v ₃|=0.00;T ₄ /G _(AA)=0.68;T ₃ /G _(AA)=0.35;|f ₄ /T ₄₋₅|=6.69;|R ₇ /f ₄|=0.56

Further, in this embodiment, “T_(L3A2-L4A1)” is equal to 0.26, and “T₄”is equal to 0.52, which is greater than “T_(L3A2-L4A1)”.

In this embodiment, the imaging lens 2 has an overall system focallength of 3.36 mm, a half field-of-view (HFOV) of 34.64°, and a systemlength of 3.59 mm. Shown in FIG. 14 is a table that shows values of theoptical parameters corresponding to the surfaces 31-71, 32-72 of thefourth preferred embodiment. Shown in FIG. 15 is a table that showsvalues of some parameters of the aforementioned optical relationship (7)corresponding to each of the object-side surfaces 31-71 and theimage-side surfaces 32-72 of the fourth preferred embodiment.

Referring to FIGS. 16( a) to 16(d), with the system length reduced downto below 4 mm, the imaging lens 2 of the fourth preferred embodiment isstill able to achieve a relatively good optical performance.

Shown in FIG. 17 is a table that shows the aforesaid relationships amongsome of the aforementioned optical parameters corresponding to thepreferred embodiments for comparison.

Effects of the various optical parameters on the imaging quality aredescribed hereinafter.

Regarding optical relationship 1, when the imaging lens 2 satisfiesoptical relationship 1 (i.e., |v₂−v₃|<10), a difference in extent ofdispersion between the second and third lens elements 4, 5 is relativelysmall, such that the refracting powers of the second lens element 4 andthe third lens element 5 may be effectively distributed.

Regarding optical relationship 2, when the imaging lens 2 satisfiesoptical relationship 2 (i.e., 0.5<T₄/G_(AA)<1.0), distribution of thethickness of the fourth lens element 6 with respect to the sum of thewidths of the air gaps among the lens elements 3-7 is optimal. When theimaging lens 2 satisfies T₄/G_(AA)≧1.0, the thickness of the fourth lenselement 6 may be too large and the radius of curvature of the same maybe too small, such that sensitivity of the imaging lens 2 to inaccuracyof the manufacturing process may be too high. On the other hand, whenthe imaging lens 2 satisfies T₄/G_(AA)≦0.5, the widths of the air gapsamong the lens elements 3-7 need to be increased, which may beunfavorable for reducing the overall system length of the imaging lens2.

When the imaging lens 2 satisfies optical relationship 3 (i.e.,0.33<T₃/G_(AA)<0.60), distribution of the thickness of the third lenselement 5 with respect to the sum of the widths of the air gaps amongthe lens elements 3-7 is optimal. When the imaging lens 2 satisfiesT₃/G_(AA)≧0.60, the widths of the air gaps among the lens elements 3-7may be too small, which may render manufacturing of the imaging lens 2difficult. On the other hand, when the imaging lens 2 satisfiesT₃/G_(AA)≦0.33, the thickness of the third lens element 5 may be toosmall, which may also render manufacturing of the imaging lens 2difficult.

Regarding optical relationship 4, when the imaging lens 2 satisfiesoptical relationship 4 (i.e., 5<|f_(t)/T₄₋₅|<8), the refracting power ofthe fourth lens element 6 has minimal influence upon distribution ofoverall refracting power of the imaging lens 2, and the distance betweenthe object-side surfaces 61, 71 of the fourth and fifth lens elements 6,7 is optimal, such that the height, at which light from the fourth lenselement 6 enters the fifth lens element 7, falls within an optimalrange. When the imaging lens 2 satisfies |f_(t)/T₄₋₅|≧8, the distancebetween the object-side surfaces 61, 71 may be too small such that theheight, at which light from the fourth lens element 6 enters the fifthlens element 7, falls outside of the optimal range. When the imaginglens 2 satisfies |f₄/T₄₋₅|≦5, the focal length of the fourth lenselement 6 may be too small and the refracting power of the same may betoo large, which may have an adverse effect on the distribution of theoverall refracting power of the imaging lens 2 and may cause severeaberration.

Regarding optical relationship 5 (i.e., 0.42<|R₇/f₄|<0.62), when theimaging lens 2 satisfies optical relationship 5, effective distributionof the overall refracting power of the imaging lens 2 may be achievedwithout increasing difficulty of manufacturing. Preferably, the imaginglens 2 satisfies 0.42<|R₇/f₄|<0.60. When the imaging lens 2 satisfies|R₇/f₄|≧0.62, the focal length of the fourth lens element 6 may be toosmall and the refracting power of the same may be too large, which mayhave an adverse effect upon the distribution of the overall refractingpower of the imaging lens 2. On the other hand, when the imaging lens 2satisfies |R₇₈/f₄|≦0.42, the radius of curvature of the object-sidesurface 61 of the fourth lens element 6 may be too small, which mayresult in increased difficulty and hence cost of manufacturing of thefourth lens element 6.

Regarding optical relationship 6, when the imaging lens 2 satisfiesoptical relationship 6 (i.e., T₄>T_(L3A2-L4A1)), the distance betweenthe third and fourth lens elements 5, 6 falls within an optimal range,thereby facilitating miniaturization of the imaging lens 2.

Aside from the above optical parameters, effects achieved throughdesigns of the object-side surfaces 31-71 and the image-side surfaces32-72 are described hereinafter.

By virtue of the positive refracting power and the convex object-sidesurface 31 of the first lens element 3, the first lens element 3 is ableto achieve a good light receiving capability and to distribute partlythe refracting power of the second lens element 4.

Through arranging the aperture stop 8 such that the first lens element 3is disposed between the aperture stop 8 and the second lens element 4,the system length of the imaging lens 2 may be effectively reduced.

By virtue of the negative refracting power and the concave image-sidesurface 42 of the second lens element 4, as well as the negativerefracting power of the third lens 5, aberration of images formed at theimage plane 10 may be effectively reduced or even eliminated.

Since the design of the convex image-side surface 62 of the fourth lenselement 6 is favorable for increasing the light receiving capability andreducing the overall system length, the concave image-side surface 61 ofthe fourth lens element 6 may be matched with the convex image-sidesurface 62 for further increasing the light receiving capability of theimaging lens 2.

The design of the concave portion 721 and the convex portion 722 of theimage-side surface 72 of the fifth lens element 7 is favorable forreducing distortion and aberration, and is capable of achieving bettercontrol of the angle of light travelling through the fifth lens element7 toward the image plane 10, at which an image sensor is to be disposed,to fall within an optimal range. In addition, the convex portion 711 ofthe object-side surface 71 of the fifth lens element 7 serves to reduceaberration.

Shown in FIG. 18 is a first exemplary application of the imaging lens 2,in which the imaging lens 2 is disposed in a housing 11 of an electronicapparatus 1 (such as a mobile phone), and forms a part of an imagingmodule 12 of the electronic apparatus 1. The imaging module 12 includesa barrel 21 on which the imaging lens 2 is disposed, a seat unit 120 onwhich the barrel 21 is disposed, and an image sensor 130 disposed at theimage plane 10 (see FIG. 1) and operatively associated with the imaginglens 2 for capturing images.

The seat unit 120 includes a first seat portion 121 in which the barrel21 is disposed, and a second seat portion 122 having a portioninterposed between the first seat portion 121 and the image sensor 130.The barrel 21 and the first seat portion 121 of the seat unit 120 extendalong an axis (II), which coincides with the optical axis (I) of theimaging lens 2.

Shown in FIG. 19 is a second exemplary application of the imaging lens2. The difference between the first and second exemplary applicationsresides in that, in the second exemplary application, the seat unit 120is configured as a voice-coil motor (VCM), and the first seat portion121 includes an inner section 123 in which the barrel 21 is disposed, anouter section 124 that surrounds the inner section 123, a coil 125 thatis interposed between the inner and outer sections 123, 124, and amagnetic component 126 that is disposed between an outer side of thecoil 125 and an inner side of the outer section 124.

The inner section 123 and the barrel 21, together with the imaging lens2 therein, are movable with respect to the image sensor 130 along anaxis (III), which coincides with the optical axis (I) of the imaginglens 2. The optical filter 9 of the imaging lens 2 is disposed at thesecond seat portion 122, which is disposed to abut against the outersection 124. Configuration and arrangement of other components of theelectronic apparatus 1 in the second exemplary application are identicalto those in the first exemplary application, and hence will not bedescribed hereinafter for the sake of brevity.

By virtue of the imaging lens 2 of the present invention, the electronicapparatus 1 in each of the exemplary applications may be configured tohave a relatively reduced overall thickness. Furthermore, applicationand configuration of the imaging lens 2 are not limited to such.

During manufacture, the first lens element 3 may be formed with anextending portion, which may be flat or stepped in shape. In terms offunction, while the object-side and image-side surfaces 31, 32 areconfigured to enable passage of light through the first lens element 3,the extending portion merely serves to provide the function ofinstallation and does not contribute toward passage of light through thefirst lens element 3. The other lens elements 4-7 may also be formedwith extending portions similar to that of the first lens element 3.

In summary, the system length of the imaging lens 2 may be reduced tobelow 4 mm without significantly compromising the optical performance ofthe imaging lens 2.

While the present invention has been described in connection with whatare considered the most practical and preferred embodiments, it isunderstood that this invention is not limited to the disclosedembodiments but is intended to cover various arrangements includedwithin the spirit and scope of the broadest interpretation so as toencompass all such modifications and equivalent arrangements.

What is claimed is:
 1. An optical imaging lens comprising, from anobject side to an image side, an aperture stop, a first lens element, asecond lens element, a third lens element, a fourth lens element, and afifth lens element, each of the first, second, third, fourth and fifthlens element having an object-side surface facing toward the object sideand an image-side surface facing toward the image side, wherein: thefirst lens element has a positive refracting power, the object-sidesurface of the first lens element has a convex portion in a vicinity ofan optical axis, and the image-side surface of the first lens elementhas a concave portion in the vicinity of the optical axis; the secondlens element has a negative refracting power and the image-side surfaceof the second lens element is concave; the image-side surface of thefourth lens element is convex; the object-side surface of the fifth lenselement has a convex portion in the vicinity of the optical axis and theimage-side of the fifth lens element has a concave portion in thevicinity of the optical axis; the optical imaging lens has only fivelens elements having a refracting power; and a ratio (T3+T4+AG23)/T1 isbetween 2.26 and 2.52, wherein T3 is a thickness of the third lenselement along the optical axis, T4 is a thickness of the fourth lenselement along the optical axis, AG23 is a width of an air gap betweenthe second and third lens element along the optical axis, and T1 is athickness of the first lens element along the optical axis.
 2. Theoptical imaging lens of claim 1, wherein a ratio (T3/GAA) is between0.33 and 0.6, wherein GAA is a sum of widths of air gaps between thefirst to fifth lens elements along the optical axis.
 3. The opticalimaging lens of claim 2, wherein a ratio (T2+GAA)/T3 is between 2.6 and3.8, wherein T2 is a thickness of the second lens element along theoptical axis.
 4. The optical imaging lens of claim 1, wherein a ratio(GAA+T4)/T3 is between 3.57 and 5.24, wherein GAA is a sum of widths ofair gaps between the first to fifth lens elements.
 5. The opticalimaging lens of claim 1, wherein a ratio (AG12+AG34+AG45)/T3 is between1.0 and 1.7, wherein AG12 is a width of an air gap between the first andsecond lens elements along the optical axis, AG34 is a width of an airgap between the third and fourth lens elements along the optical axis,and AG45 is a width of an air gap between the fourth and fifth lenselements along the optical axis.
 6. An optical imaging lens comprising,from an object side to an image side, an aperture stop, a first lenselement, a second lens element, a third lens element, a fourth lenselement, and a fifth lens element, each of the first, second, third,fourth and fifth lens element having an object-side surface facingtoward the object side and an image-side surface facing toward the imageside, wherein: the object-side surface of the first lens element has aconvex portion in a vicinity of an optical axis and the first lenselement has a positive refracting power; the image-side surface of thesecond lens element is concave and the second lens element has anegative refracting power; the image-side surface of the fourth lenselement is convex; the image-side surface of the fifth lens element hasa concave portion in the vicinity of the optical axis; the opticalimaging lens has only five lens elements having a refracting power; aratio (T3+T4+AG23)/T1 is between 2.26 and 2.52, wherein T3 is athickness of the third lens element along the optical axis, T4 is athickness of the fourth lens element along the optical axis, AG23 is awidth of an air gap between the second and third lens element along theoptical axis, and T1 is a thickness of the first lens element along theoptical axis; a ratio (GAA+T4)/T3 is between 3.57 and 5.24, wherein GAAis a sum of widths of air gaps between the first to fifth lens elementsalong the optical axis; and a ratio GAA/AG23 is between 2.1 and 2.6. 7.The optical imaging lens of claim 6, wherein a ratio (AG12+AG34+AG45)/T3is between 1.0 and 1.7, wherein AG12 is a width of an air gap betweenthe first and second lens elements along the optical axis, AG34 is awidth of an air gap between the third and fourth lens elements along theoptical axis, and AG45 is a width of an air gap between the fourth andfifth lens elements.
 8. The optical imaging lens of claim 7, wherein aratio (T2+AG23)/T3 is between 1.6 and 2.3, wherein T2 is a thickness ofthe second lens element along the optical axis.
 9. The optical imaginglens of claim 6, wherein a ratio (GAA+T2)/AG23 is between 2.9 and 3.4,wherein T2 is a thickness of the second lens element along the opticalaxis.
 10. The optical imaging lens of claim 6, wherein a ratio(T2+GAA)/T3 is between 2.6 and 3.8, wherein T2 is a thickness of thesecond lens element along the optical axis.
 11. An optical imaging lenscomprising, from an object side to an image side, an aperture stop, afirst lens element, a second lens element, a third lens element, afourth lens element, and a fifth lens element, each of the first,second, third, fourth and fifth lens element having an object-sidesurface facing toward the object side and an image-side surface facingtoward the image side, wherein: the first lens element has a positiverefracting power, the object-side surface of the first imaging lens hasa convex portion in a vicinity of an optical axis, and the image-sidesurface of the first imaging lens has a concave portion in the vicinityof the optical axis; the second lens element has a negative refractingpower and the image-side surface of the second lens element is concave;the image-side surface of the fourth lens element is convex; theimage-side surface of the fifth lens element has a concave portion inthe vicinity of the optical axis; the optical imaging lens has only fivelens elements having a refracting power; a ratio (GAA+T4)/T3 is between3.57 and 5.24, wherein GAA is a sum of widths of air gaps between thefirst to fifth lens elements along the optical axis, T4 is a thicknessof the fourth lens element along the optical axis, and T3 is a thicknessof the third lens element along the optical axis; and a ratio(AG12+AG34+AG45)/T3 is between 1.0 and 1.7, wherein AG12 is a width ofan air gap between the first and second lens elements along the opticalaxis, AG34 is a width of an air gap between the third and fourth lenselements along the optical axis, and AG45 is a width of an air gapbetween the fourth and fifth lens elements along the optical axis. 12.The optical imaging lens of claim 11, wherein a ratio (T3/GAA) isbetween 0.33 and 0.6.
 13. The optical imaging lens of claim 12, whereina ratio GAA/AG23 is between 2.1 and 2.6, wherein AG23 is a width of anair gap between the second and third lens elements along the opticalaxis.
 14. The optical imaging lens of claim 11, wherein a ratio(T2+AG23)/T3 is between 1.6 and 2.3, wherein T2 is a thickness of thesecond lens element along the optical axis and AG23 is a width of an airgap between the second and third lens elements along the optical axis.15. The optical imaging lens of claim 11, wherein a ratio (T2+GAA)/T3 isbetween 2.6 and 3.8, wherein T2 is a thickness of the second lenselement along the optical axis.